The department of the United States federal government that exists to serve the needs of those engaged in agriculture and rural communities. It comprises a number of agencies, each with its own functions, one of which is the US Soil Survey. In 1960, the USDA published Soil Classification: A Comprehensive System, prepared by the Soil Survey. This method of classifying soils hierarchically was renamed the US Soil Taxonomy in 1970, and was the most widely used taxonomic system prior to the introduction of the international soil classification developed by the FAO. See soil taxonomy; world reference base for soil resources.